Logic for finding frame references moved from PacketBuffer to new class

webrtc/modules/video_coding/packet_buffer.cc

Index: webrtc/modules/video_coding/packet_buffer.cc
diff --git a/webrtc/modules/video_coding/packet_buffer.cc b/webrtc/modules/video_coding/packet_buffer.cc
index 71ab3e57d859fe20a5d518cb3a96856280c3fc1e..09fb2499074fde1b12005d427b9cdba5dd81a18c 100644
--- a/webrtc/modules/video_coding/packet_buffer.cc
+++ b/webrtc/modules/video_coding/packet_buffer.cc
@@ -30,10 +30,7 @@ PacketBuffer::PacketBuffer(size_t start_buffer_size,
       first_packet_received_(false),
       data_buffer_(start_buffer_size),
       sequence_buffer_(start_buffer_size),
-      frame_callback_(frame_callback),
-      last_picture_id_(-1),
-      last_unwrap_(-1),
-      current_ss_idx_(0) {
+      reference_finder_(frame_callback) {
   RTC_DCHECK_LE(start_buffer_size, max_buffer_size);
   // Buffer size must always be a power of 2.
   RTC_DCHECK((start_buffer_size & (start_buffer_size - 1)) == 0);
@@ -152,7 +149,7 @@ void PacketBuffer::FindFrames(uint16_t seq_num) {
 
       std::unique_ptr<RtpFrameObject> frame(
           new RtpFrameObject(this, start_seq_num, seq_num));
-      ManageFrame(std::move(frame));
+      reference_finder_.ManageFrame(std::move(frame));
     }
 
     index = (index + 1) % size_;
@@ -204,468 +201,21 @@ bool PacketBuffer::GetBitstream(const RtpFrameObject& frame,
   return true;
 }
 
-void PacketBuffer::ManageFrame(std::unique_ptr<RtpFrameObject> frame) {
-  size_t start_index = frame->first_seq_num() % size_;
-  VideoCodecType codec_type = data_buffer_[start_index].codec;
-
-  switch (codec_type) {
-    case kVideoCodecULPFEC:
-    case kVideoCodecRED:
-    case kVideoCodecUnknown:
-      RTC_NOTREACHED();
-      break;
-    case kVideoCodecVP8:
-      ManageFrameVp8(std::move(frame));
-      break;
-    case kVideoCodecVP9:
-      ManageFrameVp9(std::move(frame));
-      break;
-    case kVideoCodecH264:
-    case kVideoCodecI420:
-    case kVideoCodecGeneric:
-      ManageFrameGeneric(std::move(frame));
-      break;
-  }
-}
-
-void PacketBuffer::RetryStashedFrames() {
-  size_t num_stashed_frames = stashed_frames_.size();
-
-  // Clean up stashed frames if there are too many.
-  while (stashed_frames_.size() > kMaxStashedFrames)
-    stashed_frames_.pop();
-
-  // Since frames are stashed if there is not enough data to determine their
-  // frame references we should at most check |stashed_frames_.size()| in
-  // order to not pop and push frames in and endless loop.
-  for (size_t i = 0; i < num_stashed_frames && !stashed_frames_.empty(); ++i) {
-    std::unique_ptr<RtpFrameObject> frame = std::move(stashed_frames_.front());
-    stashed_frames_.pop();
-    ManageFrame(std::move(frame));
-  }
-}
-
-void PacketBuffer::ManageFrameGeneric(
-    std::unique_ptr<RtpFrameObject> frame) {
-  size_t index = frame->first_seq_num() % size_;
-  const VCMPacket& packet = data_buffer_[index];
-
-  if (packet.frameType == kVideoFrameKey)
-    last_seq_num_gop_[frame->last_seq_num()] = frame->last_seq_num();
-
-  // We have received a frame but not yet a keyframe, stash this frame.
-  if (last_seq_num_gop_.empty()) {
-    stashed_frames_.emplace(std::move(frame));
-    return;
-  }
-
-  // Clean up info for old keyframes but make sure to keep info
-  // for the last keyframe.
-  auto clean_to = last_seq_num_gop_.lower_bound(frame->last_seq_num() - 100);
-  if (clean_to != last_seq_num_gop_.end())
-    last_seq_num_gop_.erase(last_seq_num_gop_.begin(), clean_to);
-
-  // Find the last sequence number of the last frame for the keyframe
-  // that this frame indirectly references.
-  auto seq_num_it = last_seq_num_gop_.upper_bound(frame->last_seq_num());
-  seq_num_it--;
-
-  // Make sure the packet sequence numbers are continuous, otherwise stash
-  // this frame.
-  if (packet.frameType == kVideoFrameDelta) {
-    if (seq_num_it->second !=
-        static_cast<uint16_t>(frame->first_seq_num() - 1)) {
-      stashed_frames_.emplace(std::move(frame));
-      return;
-    }
-  }
-
-  RTC_DCHECK(AheadOrAt(frame->last_seq_num(), seq_num_it->first));
-
-  // Since keyframes can cause reordering of the frames delivered from
-  // FindFrames() we can't simply assign the picture id according to some
-  // incrementing counter.
-  frame->picture_id = frame->last_seq_num();
-  frame->num_references = packet.frameType == kVideoFrameDelta;
-  frame->references[0] = seq_num_it->second;
-  seq_num_it->second = frame->picture_id;
-
-  last_picture_id_ = frame->picture_id;
-  frame_callback_->OnCompleteFrame(std::move(frame));
-  RetryStashedFrames();
-}
-
-void PacketBuffer::ManageFrameVp8(std::unique_ptr<RtpFrameObject> frame) {
-  size_t index = frame->first_seq_num() % size_;
-  const VCMPacket& packet = data_buffer_[index];
-  const RTPVideoHeaderVP8& codec_header =
-      packet.codecSpecificHeader.codecHeader.VP8;
-
-  if (codec_header.pictureId == kNoPictureId ||
-      codec_header.temporalIdx == kNoTemporalIdx ||
-      codec_header.tl0PicIdx == kNoTl0PicIdx) {
-    ManageFrameGeneric(std::move(frame));
-    return;
-  }
-
-  frame->picture_id = codec_header.pictureId % kPicIdLength;
-
-  if (last_unwrap_ == -1)
-    last_unwrap_ = codec_header.pictureId;
-
-  if (last_picture_id_ == -1)
-    last_picture_id_ = frame->picture_id;
-
-  // Find if there has been a gap in fully received frames and save the picture
-  // id of those frames in |not_yet_received_frames_|.
-  if (AheadOf<uint16_t, kPicIdLength>(frame->picture_id, last_picture_id_)) {
-    last_picture_id_ = Add<kPicIdLength>(last_picture_id_, 1);
-    while (last_picture_id_ != frame->picture_id) {
-      not_yet_received_frames_.insert(last_picture_id_);
-      last_picture_id_ = Add<kPicIdLength>(last_picture_id_, 1);
-    }
-  }
-
-  // Clean up info for base layers that are too old.
-  uint8_t old_tl0_pic_idx = codec_header.tl0PicIdx - kMaxLayerInfo;
-  auto clean_layer_info_to = layer_info_.lower_bound(old_tl0_pic_idx);
-  layer_info_.erase(layer_info_.begin(), clean_layer_info_to);
-
-  // Clean up info about not yet received frames that are too old.
-  uint16_t old_picture_id = Subtract<kPicIdLength>(frame->picture_id,
-                                                   kMaxNotYetReceivedFrames);
-  auto clean_frames_to = not_yet_received_frames_.lower_bound(old_picture_id);
-  not_yet_received_frames_.erase(not_yet_received_frames_.begin(),
-                                 clean_frames_to);
-
-  if (packet.frameType == kVideoFrameKey) {
-    frame->num_references = 0;
-    layer_info_[codec_header.tl0PicIdx].fill(-1);
-    CompletedFrameVp8(std::move(frame));
-    return;
-  }
-
-  auto layer_info_it = layer_info_.find(codec_header.temporalIdx == 0
-                                            ? codec_header.tl0PicIdx - 1
-                                            : codec_header.tl0PicIdx);
-
-  // If we don't have the base layer frame yet, stash this frame.
-  if (layer_info_it == layer_info_.end()) {
-    stashed_frames_.emplace(std::move(frame));
-    return;
-  }
-
-  // A non keyframe base layer frame has been received, copy the layer info
-  // from the previous base layer frame and set a reference to the previous
-  // base layer frame.
-  if (codec_header.temporalIdx == 0) {
-    layer_info_it =
-        layer_info_
-            .insert(make_pair(codec_header.tl0PicIdx, layer_info_it->second))
-            .first;
-    frame->num_references = 1;
-    frame->references[0] = layer_info_it->second[0];
-    CompletedFrameVp8(std::move(frame));
-    return;
-  }
-
-  // Layer sync frame, this frame only references its base layer frame.
-  if (codec_header.layerSync) {
-    frame->num_references = 1;
-    frame->references[0] = layer_info_it->second[0];
-
-    CompletedFrameVp8(std::move(frame));
-    return;
-  }
-
-  // Find all references for this frame.
-  frame->num_references = 0;
-  for (uint8_t layer = 0; layer <= codec_header.temporalIdx; ++layer) {
-    RTC_DCHECK_NE(-1, layer_info_it->second[layer]);
-
-    // If we have not yet received a frame between this frame and the referenced
-    // frame then we have to wait for that frame to be completed first.
-    auto not_received_frame_it =
-             not_yet_received_frames_.upper_bound(layer_info_it->second[layer]);
-    if (not_received_frame_it != not_yet_received_frames_.end() &&
-        AheadOf<uint16_t, kPicIdLength>(frame->picture_id,
-                                        *not_received_frame_it)) {
-      stashed_frames_.emplace(std::move(frame));
-      return;
-    }
-
-    ++frame->num_references;
-    frame->references[layer] = layer_info_it->second[layer];
-  }
-
-  CompletedFrameVp8(std::move(frame));
-}
-
-void PacketBuffer::CompletedFrameVp8(std::unique_ptr<RtpFrameObject> frame) {
-  size_t index = frame->first_seq_num() % size_;
-  const VCMPacket& packet = data_buffer_[index];
-  const RTPVideoHeaderVP8& codec_header =
-      packet.codecSpecificHeader.codecHeader.VP8;
-
-  uint8_t tl0_pic_idx = codec_header.tl0PicIdx;
-  uint8_t temporal_index = codec_header.temporalIdx;
-  auto layer_info_it = layer_info_.find(tl0_pic_idx);
-
-  // Update this layer info and newer.
-  while (layer_info_it != layer_info_.end()) {
-    if (layer_info_it->second[temporal_index] != -1 &&
-        AheadOf<uint16_t, kPicIdLength>(layer_info_it->second[temporal_index],
-                                        frame->picture_id)) {
-      // The frame was not newer, then no subsequent layer info have to be
-      // update.
-      break;
-    }
-
-    layer_info_it->second[codec_header.temporalIdx] = frame->picture_id;
-    ++tl0_pic_idx;
-    layer_info_it = layer_info_.find(tl0_pic_idx);
-  }
-  not_yet_received_frames_.erase(frame->picture_id);
-
-  for (size_t i = 0; i < frame->num_references; ++i)
-    frame->references[i] = UnwrapPictureId(frame->references[i]);
-  frame->picture_id = UnwrapPictureId(frame->picture_id);
-
-  frame_callback_->OnCompleteFrame(std::move(frame));
-  RetryStashedFrames();
-}
-
-void PacketBuffer::ManageFrameVp9(std::unique_ptr<RtpFrameObject> frame) {
-  size_t index = frame->first_seq_num() % size_;
-  const VCMPacket& packet = data_buffer_[index];
-  const RTPVideoHeaderVP9& codec_header =
-      packet.codecSpecificHeader.codecHeader.VP9;
-
-  if (codec_header.picture_id == kNoPictureId) {
-    ManageFrameGeneric(std::move(frame));
-    return;
-  }
-
-  frame->spatial_layer = codec_header.spatial_idx;
-  frame->inter_layer_predicted = codec_header.inter_layer_predicted;
-  frame->picture_id = codec_header.picture_id % kPicIdLength;
-
-  if (last_unwrap_ == -1)
-    last_unwrap_ = codec_header.picture_id;
-
-  if (last_picture_id_ == -1)
-    last_picture_id_ = frame->picture_id;
-
-  if (codec_header.flexible_mode) {
-    frame->num_references = codec_header.num_ref_pics;
-    for (size_t i = 0; i < frame->num_references; ++i) {
-      frame->references[i] =
-          Subtract<1 << 16>(frame->picture_id, codec_header.pid_diff[i]);
-    }
-
-    CompletedFrameVp9(std::move(frame));
-    return;
-  }
-
-  if (codec_header.ss_data_available) {
-    // Scalability structures can only be sent with tl0 frames.
-    if (codec_header.temporal_idx != 0) {
-      LOG(LS_WARNING) << "Received scalability structure on a non base layer"
-                         " frame. Scalability structure ignored.";
-    } else {
-      current_ss_idx_ = Add<kMaxGofSaved>(current_ss_idx_, 1);
-      scalability_structures_[current_ss_idx_] = codec_header.gof;
-      scalability_structures_[current_ss_idx_].pid_start = frame->picture_id;
-
-      auto pid_and_gof = std::make_pair(
-          frame->picture_id, &scalability_structures_[current_ss_idx_]);
-      gof_info_.insert(std::make_pair(codec_header.tl0_pic_idx, pid_and_gof));
-    }
-  }
-
-  // Clean up info for base layers that are too old.
-  uint8_t old_tl0_pic_idx = codec_header.tl0_pic_idx - kMaxGofSaved;
-  auto clean_gof_info_to = gof_info_.lower_bound(old_tl0_pic_idx);
-  gof_info_.erase(gof_info_.begin(), clean_gof_info_to);
-
-  if (packet.frameType == kVideoFrameKey) {
-    // When using GOF all keyframes must include the scalability structure.
-    if (!codec_header.ss_data_available)
-      LOG(LS_WARNING) << "Received keyframe without scalability structure";
-
-    frame->num_references = 0;
-    GofInfoVP9* gof = gof_info_.find(codec_header.tl0_pic_idx)->second.second;
-    FrameReceivedVp9(frame->picture_id, *gof);
-    CompletedFrameVp9(std::move(frame));
-    return;
-  }
-
-  auto gof_info_it = gof_info_.find(
-      (codec_header.temporal_idx == 0 && !codec_header.ss_data_available)
-          ? codec_header.tl0_pic_idx - 1
-          : codec_header.tl0_pic_idx);
-
-  // Gof info for this frame is not available yet, stash this frame.
-  if (gof_info_it == gof_info_.end()) {
-    stashed_frames_.emplace(std::move(frame));
-    return;
-  }
-
-  GofInfoVP9* gof = gof_info_it->second.second;
-  uint16_t picture_id_tl0 = gof_info_it->second.first;
-
-  FrameReceivedVp9(frame->picture_id, *gof);
-
-  // Make sure we don't miss any frame that could potentially have the
-  // up switch flag set.
-  if (MissingRequiredFrameVp9(frame->picture_id, *gof)) {
-    stashed_frames_.emplace(std::move(frame));
-    return;
-  }
-
-  if (codec_header.temporal_up_switch) {
-    auto pid_tidx =
-        std::make_pair(frame->picture_id, codec_header.temporal_idx);
-    up_switch_.insert(pid_tidx);
-  }
-
-  // If this is a base layer frame that contains a scalability structure
-  // then gof info has already been inserted earlier, so we only want to
-  // insert if we haven't done so already.
-  if (codec_header.temporal_idx == 0 && !codec_header.ss_data_available) {
-    auto pid_and_gof = std::make_pair(frame->picture_id, gof);
-    gof_info_.insert(std::make_pair(codec_header.tl0_pic_idx, pid_and_gof));
-  }
-
-  // Clean out old info about up switch frames.
-  uint16_t old_picture_id = Subtract<kPicIdLength>(last_picture_id_, 50);
-  auto up_switch_erase_to = up_switch_.lower_bound(old_picture_id);
-  up_switch_.erase(up_switch_.begin(), up_switch_erase_to);
-
-  RTC_DCHECK(
-      (AheadOrAt<uint16_t, kPicIdLength>(frame->picture_id, picture_id_tl0)));
-
-  size_t diff =
-      ForwardDiff<uint16_t, kPicIdLength>(gof->pid_start, frame->picture_id);
-  size_t gof_idx = diff % gof->num_frames_in_gof;
-
-  // Populate references according to the scalability structure.
-  frame->num_references = gof->num_ref_pics[gof_idx];
-  for (size_t i = 0; i < frame->num_references; ++i) {
-    frame->references[i] =
-        Subtract<kPicIdLength>(frame->picture_id, gof->pid_diff[gof_idx][i]);
-
-    // If this is a reference to a frame earlier than the last up switch point,
-    // then ignore this reference.
-    if (UpSwitchInIntervalVp9(frame->picture_id, codec_header.temporal_idx,
-                              frame->references[i])) {
-      --frame->num_references;
-    }
-  }
-
-  CompletedFrameVp9(std::move(frame));
-}
-
-bool PacketBuffer::MissingRequiredFrameVp9(uint16_t picture_id,
-                                           const GofInfoVP9& gof) {
-  size_t diff = ForwardDiff<uint16_t, kPicIdLength>(gof.pid_start, picture_id);
-  size_t gof_idx = diff % gof.num_frames_in_gof;
-  size_t temporal_idx = gof.temporal_idx[gof_idx];
-
-  // For every reference this frame has, check if there is a frame missing in
-  // the interval (|ref_pid|, |picture_id|) in any of the lower temporal
-  // layers. If so, we are missing a required frame.
-  uint8_t num_references = gof.num_ref_pics[gof_idx];
-  for (size_t i = 0; i < num_references; ++i) {
-    uint16_t ref_pid =
-        Subtract<kPicIdLength>(picture_id, gof.pid_diff[gof_idx][i]);
-    for (size_t l = 0; l < temporal_idx; ++l) {
-      auto missing_frame_it = missing_frames_for_layer_[l].lower_bound(ref_pid);
-      if (missing_frame_it != missing_frames_for_layer_[l].end() &&
-          AheadOf<uint16_t, kPicIdLength>(picture_id, *missing_frame_it)) {
-        return true;
-      }
-    }
-  }
-  return false;
-}
-
-void PacketBuffer::FrameReceivedVp9(uint16_t picture_id,
-                                    const GofInfoVP9& gof) {
-  RTC_DCHECK_NE(-1, last_picture_id_);
-
-  // If there is a gap, find which temporal layer the missing frames
-  // belong to and add the frame as missing for that temporal layer.
-  // Otherwise, remove this frame from the set of missing frames.
-  if (AheadOf<uint16_t, kPicIdLength>(picture_id, last_picture_id_)) {
-    size_t diff =
-        ForwardDiff<uint16_t, kPicIdLength>(gof.pid_start, last_picture_id_);
-    size_t gof_idx = diff % gof.num_frames_in_gof;
-
-    last_picture_id_ = Add<kPicIdLength>(last_picture_id_, 1);
-    while (last_picture_id_ != picture_id) {
-      ++gof_idx;
-      RTC_DCHECK_NE(0ul, gof_idx % gof.num_frames_in_gof);
-      size_t temporal_idx = gof.temporal_idx[gof_idx];
-      missing_frames_for_layer_[temporal_idx].insert(last_picture_id_);
-      last_picture_id_ = Add<kPicIdLength>(last_picture_id_, 1);
-    }
-  } else {
-    size_t diff =
-        ForwardDiff<uint16_t, kPicIdLength>(gof.pid_start, picture_id);
-    size_t gof_idx = diff % gof.num_frames_in_gof;
-    size_t temporal_idx = gof.temporal_idx[gof_idx];
-    missing_frames_for_layer_[temporal_idx].erase(picture_id);
-  }
-}
-
-bool PacketBuffer::UpSwitchInIntervalVp9(uint16_t picture_id,
-                                         uint8_t temporal_idx,
-                                         uint16_t pid_ref) {
-  for (auto up_switch_it = up_switch_.upper_bound(pid_ref);
-       up_switch_it != up_switch_.end() &&
-       AheadOf<uint16_t, kPicIdLength>(picture_id, up_switch_it->first);
-       ++up_switch_it) {
-    if (up_switch_it->second < temporal_idx)
-      return true;
+VCMPacket* PacketBuffer::GetPacket(uint16_t seq_num) {
+  rtc::CritScope lock(&crit_);
+  size_t index = seq_num % size_;
+  if (!sequence_buffer_[index].used ||
+      seq_num != sequence_buffer_[index].seq_num) {
+    return nullptr;
   }
-
-  return false;
-}
-
-void PacketBuffer::CompletedFrameVp9(std::unique_ptr<RtpFrameObject> frame) {
-  for (size_t i = 0; i < frame->num_references; ++i)
-    frame->references[i] = UnwrapPictureId(frame->references[i]);
-  frame->picture_id = UnwrapPictureId(frame->picture_id);
-
-  frame_callback_->OnCompleteFrame(std::move(frame));
-  RetryStashedFrames();
+  return &data_buffer_[index];
 }
 
-uint16_t PacketBuffer::UnwrapPictureId(uint16_t picture_id) {
-  RTC_DCHECK_NE(-1, last_unwrap_);
-
-  uint16_t unwrap_truncated = last_unwrap_ % kPicIdLength;
-  uint16_t diff = MinDiff<uint16_t, kPicIdLength>(unwrap_truncated, picture_id);
-
-  if (AheadOf<uint16_t, kPicIdLength>(picture_id, unwrap_truncated))
-    last_unwrap_ = Add<1 << 16>(last_unwrap_, diff);
-  else
-    last_unwrap_ = Subtract<1 << 16>(last_unwrap_, diff);
-
-  return last_unwrap_;
-}
-
-void PacketBuffer::Flush() {
+void PacketBuffer::Clear() {
   rtc::CritScope lock(&crit_);
   for (size_t i = 0; i < size_; ++i)
     sequence_buffer_[i].used = false;
 
-  last_seq_num_gop_.clear();
-  while (!stashed_frames_.empty())
-    stashed_frames_.pop();
-  not_yet_received_frames_.clear();
-
   first_packet_received_ = false;
 }